A scanned image from a Kamen Rider Ganbarizing leaflet has surfaced feat the secondary rider for the series, Kamen Rider Cross-Z and the newest Best Match forms for Kamen Rider Build!
As recently revealed, the correct pronunciation for the secondary Rider's name is Kamen Rider Cross-Z, and Ryuga Banjo has been confirmed to be the one to transform into Cross-Z and he is ready to debut next month.

As for the newest Best Match form for Kamen Rider Build, we have the PirateTrain, which uses the element of the Pirate and Train Full Bottles, and the KeyDragon form, which uses the element of the Lock and Dragon Full Bottles.